From: Alex Deucher
The vram scratch was originally only used on some 7xx asics
to work around a hw bug. Allocate the scratch page on all 6xx+
radeons and set the MC_VM_SYSTEM_APERTURE_DEFAULT_ADDR to point
to it. We shouldn't ever hit it since we limit the system
aperture to vram or vram and AG
From: Alex Deucher
The vram scratch was originally only used on some 7xx asics
to work around a hw bug. Allocate the scratch page on all 6xx+
radeons and set the MC_VM_SYSTEM_APERTURE_DEFAULT_ADDR to point
to it. We shouldn't ever hit it since we limit the system
aperture to vram or vram and AG
